Many different technologies have been developed for fabricating switches and relays for low frequency and high frequency switching applications. Many of these technologies rely on solid, mechanical contacts that are alternatively actuated from one position to another to make and break electrical contact. Unfortunately, mechanical switches that rely on solid-solid contact are prone to wear and are subject to a condition known as “fretting.” Fretting refers to erosion that occurs at the points of contact on surfaces. Fretting of the contacts is likely to occur under load and in the presence of repeated relative surface motion. Fretting typically manifests as pits or grooves on the contact surfaces and results in the formation of debris that may lead to shorting of the switch or relay.
To minimize mechanical damage imparted to switch and relay contacts, switches and relays have been fabricated using liquid metals to wet the movable mechanical structures to prevent solid to solid contact. Unfortunately, as switches and relays employing movable mechanical structures for actuation are scaled to sub-millimeter sizes, challenges in fabrication, reliability and operation begin to appear. Micromachining fabrication processes exist to build micro-scale liquid metal switches and relays that use the liquid metal to wet the movable mechanical structures, but devices that employ mechanical moving parts can be overly-complicated, thus reducing the yield of devices fabricated using these technologies. A liquid metal switch with no mechanical moving parts is disclosed in U.S. patent application Ser. No. 10/996,823, entitled “Liquid Metal Switch Employing Electrowetting For Actuation And Architectures For Implementing Same,” filed on Nov. 24, 2004, assigned to the assignee of the instant application, and is incorporated herein by reference. In the above-identified application, a liquid metal switch is actuated using what is referred to as “electrowetting.” To actuate a liquid metal switch using electrowetting, an electric field is generated in the vicinity of a droplet of electrically conductive liquid. The electric field causes the droplet to deform and translate across a surface. However, a radio frequency (RF) signal that is being switched by the droplet is susceptible to capacitive coupling into the circuitry that controls the electric field in the vicinity of the droplet. Therefore, it would be desirable to prevent the RF signal from capacitively coupling into the control circuitry of the liquid metal switch.